Update @ 9:00 a.m. 3/21/2012: Fort Worth police spokesman Sgt. Pedro Criado says officers have arrested one man in connection with the incident. We expect to learn more from police at a 10 a.m. news conference they have scheduled.

FORT WORTH (CBSDFW.COM) – At least one ignited, fuel-filled bottle was left at the foot of the door of State Sen. Wendy Davis’ Fort Worth district offices Tuesday afternoon, a spokesman said.

No one was injured and Davis was not present during the incident.

The device, known as a Molotov cocktail, was thrown at the front door of Davis’ third floor office in the West 7th area near Montgomery Plaza.

At least one Molotov cocktail was hurled at Sen. Wendy Davis's Fort Worth office on March 20, 2012. This is the aftermath. (Credit: Twitter, @RyanJCormier)

Anthony Spangler, the senator’s communications director, said a staffer reported hearing a large thud at the door, followed shortly by the building’s fire alarm. He said it appeared there was more than one device, but was unsure exactly how many.

“I don’t think anyone is certain whether they were thrown against the door or dropped in front of the door,” Spangler said. “There was a loud thud, which led folks to believe it was thrown at the door.”

Raw interview with Davis’ spokesman Anthony Spangler:

The staffer opened the door to find the bottle spewing waist-high flames. Another staffer then jumped over the fire to escape the building while the other individual doused the blaze with a fire extinguisher.

Spangler says Davis was not at her office and no staffers or other individuals in the building were injured.

“Our office is open to the public all the time and people can come and go freely in the building, as is the case in many government offices,” Spangler said.

The Fort Worth Fire Department says an arson investigation is now underway. State Troopers and the Fort Worth Police Department are assisting in the investigation.

Witnesses were unable to give a specific description of the suspect, but did say a maintenance worker in the building attempted to stop the person from running away. Spangler was unsure whether cameras captured the act.

He said Davis was briefed on the situation and is safe.

“We quickly made sure her safety was accounted for,” Spangler said. “DPS has been informed and we’re certain her safety is secure at this time.”

In an evening press conference, Davis told reporters that DPS troopers had her under lockdown for nearly four hours until they were sure there was no longer a threat to her safety.

“Our office was a victim of a violent act, which was alarm and very scary for my staff to say the least,” she said. “It’s a sad but true fact of public service that we have to feel concern sometimes for our public safety.”

Davis said her office will be open Thursday morning, as normal.

A valet attendant told investigators he saw a maintenance man chasing another man out of the building shortly after the incident. Police did not immediately release a specific description of a suspect Tuesday night.